Evaporator for a refrigeration system

ABSTRACT

An evaporator for a refrigeration system includes a baffle plate extending over a portion of a tube bundle assembly, the baffle plate assisting in directing a fluid flow from a tube first portion to a tube second portion. A method of forming an evaporator is further included.

TECHNICAL FIELD

The present invention relates to refrigeration systems. More particularly, the present invention relates to evaporators for centrifugal compressor refrigeration systems.

BACKGROUND OF THE INVENTION

Centrifugal chillers, which are the workhorses of the comfort cooling industry, have very few moving parts (Prior Art FIG. 1). Therefore, they usually offer high reliability and low maintenance requirements. A centrifugal compressor of the centrifugal chiller acts very much like a centrifugal fan, compressing the vapor flowing through it by spinning it from the center of an impeller wheel radially outward, allowing centrifugal forces to compress the vapor. Some machines use multiple impellers to compress the refrigerant in stages.

The compressor is in fluid communication with an evaporator, as depicted in prior art FIG. 2. The evaporator acts to change the state of a refrigerant from a liquid to a vapor by warming the refrigerant. The refrigerant vapor exits the evaporator at a suction nozzle under the motive force of a suction applied thereto by the compressor. It is important for the operating life of the compressor that an liquid refrigerant passing out through the suction nozzle be absolutely minimized, such liquid having a deleterious effect on compressor components.

There is a need in the industry to make a more tolerated evaporator for liquid carry-over and less pressure drop in the waterside. Liquid carry-over, as noted above, has the potential for damaging or reducing the life of centrifugal compressors. Further, liquid carry-over reduces the cooling capacity and efficiency of the refrigeration system.

SUMMARY OF THE INVENTION

The present invention substantially meets the aforementioned needs of the industry. The present invention affords the following advantages as compared to prior art refrigeration systems:

Less pressure drop;

Reduced liquid carry-over;

More efficient evaporator and tolerated evaporator for carry-over; and

Utilizes fewer tubes for the same shell length.

Further potential advantages include:

The drop liquid may heated near the shell support plate by water under the baffle plate; and

The shell head near the suction nozzle may not be needed.

The present invention is an evaporator for a refrigeration system, including a baffle plate extending over a portion of a tube bundle assembly, the baffle plate preventing liquid refrigerant carried over by suction nozzle above, the baffle plate assisting in directing a fluid flow from a tube first portion to a tube second portion. The present invention is further a method of forming an evaporator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially cut away depiction of a prior art centrifugal compressor refrigeration system;

FIG. 2 is perspective view of a cut away prior art evaporator; and

FIG. 3 is a cut away perspective view of an evaporator of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

The evaporator of the present invention is shown generally at 10 in FIG. 2. Evaporator 10 is intended to be employed in a refrigeration system such as depicted in Prior Art FIG. 1. Such refrigeration system can be configured to employ the present invention simply by replacing the evaporator depicted in FIG. 1 with the evaporator 10 of the present invention.

The evaporator 10 has two major subcomponents: shell assembly 12 and tube bundle assembly 14.

The shell assembly 12 of the evaporator 10 includes a cylindrical shell 16. Typically, the shell assembly 12 is 9 to 16 feet in length. The cylindrical shell 16 is sealingly capped at either end by a shell head 68. The shell support plate 18 of FIG. 3 is the leftmost shell support plate 18 of the evaporator 10, the rightmost shell support plate 18 not be depicted. Each of the shell support plates 18 is a solid rectangular plate for fluidly sealing the interior cavity 22 defined with the cylindrical shell 16. A plurality of bores 20 are defined in shell support plate 18 for bolting the shell support plate 18 to the respective end of the cylindrical shell 16. A refrigerant suction nozzle 24 is disposed on the upper surface of the cylindrical shell 16 proximate the leftmost shell support plate 18. The refrigerant inlet 78 is at the bottom of the shell 16.

The second subcomponent of the evaporator 10 is the tube bundle assembly 14. The tube bundle assembly 14 includes lower portion tubes 26 and upper portion tubes 28. The tube ends 30 of the tubes 26, 28 are expanded and sealed at tube sheet 32. The tube sheet 32 is spaced apart from the inner margin of the shell support plate 18. A plurality of spaced apart tube supports 34 extend the length of the shell assembly 12 to support the tube bundle assembly 14.

A water pass vane 36 is disposed leftward of the tube sheet 32. The water pass vane 36 provides for the demarcation between the lower portion tubes 26 and the upper portion tubes 28 in an evaporator in which the liquid refrigerant flows in at the bottom and refrigerant vapor flows out at the top, as depicted in FIG. 1. It is understood that the configuration of the present invention can be rotated 90 degrees to define a side to side type evaporator. The water pass vane is then positioned vertically so that the water passage is from side to side.

The water pass vane 36 is generally rectangular and has spaced apart parallel side margins 38. Each of the two side margins 38 is sealingly coupled to the interior margin of the cylindrical shell 16. The distal margin 40 of the water pass vane 36 is fixedly coupled to the tube sheet 32. The proximal margin 42 of the water pass vane 36 extends leftward therefrom and is spaced apart from the interior margin of the shell support plate 18. The proximal margin 42 in cooperation with the interior margin of the shell support plate 18 in part define a water passageway 44 between the lower portion tubes 26 and the upper portion tubes 28.

Two sides of the baffle plate are welded on the inside surface of the shell. The bottom surface of the baffle plate 46 is welded on the top of the tube sheet 32. The front edge of the baffle plate is welded on the shell support plate 18. The end of tubes are expanded to seal in the tube sheet 32. Water passage can be used side by side also. A baffle plate 46 is disposed at the leftmost portion of the cylindrical shell 16. The baffle plate 46 overlies the uppermost layer of tubes of the upper portion tubes 28.

The baffle plate 46 is generally rectangular in shape and has opposed, spaced apart side margins 48 that extend to and are sealingly coupled with the interior margin of the cylindrical shell 16. The distal end 50 of the baffle plate 46 extends rightward a portion of the length of the cylindrical shell 16. Preferably, the distal end 50 is located between a ¼ and a ⅓ of the length of the cylindrical shell 16. Accordingly, in an evaporator that is 9 to 16 feet long, the length dimension of the baffle plate 46 is preferably 3 to 4 feet. The proximal end 52 of the baffle plate 46 is sealingly coupled to the interior margin of the leftmost shell support plate 18.

In operation, the interior cavity 22 of the shell assembly 12 is flooded with refrigerant. Chilled water is introduced to the lower portion tubes 26 of the tube bundle assembly 14 proximate the rightmost shell support plate 18. The chilled water makes a first pass through the lower portion tubes 26 as indicated by the arrow 54, cooling the water and evaporating the refrigerant. Upon passing through the tube ends 30 of the lower portion tubes 26, the water passes around the proximal end 42 of the water pass vane 36 through the water passage 44, as indicated by the arrow 58. The now somewhat warmed water enters the tube ends 30 of the upper portion tubes 28 and makes a second pass through the upper portion tubes 28 as indicated by the arrow 58 and is then extracted from the evaporator 10. This pass further cools the water. The baffle plate 48 acts to keep the water below the baffle plate 48 in its transition from the lower portion tubes 26 to the upper portion tubes 28. Refrigerant vapor passes leftward through the upper portion of the interior cavity 22 and is drawn out of the suction nozzle 24.

The above disclosure is not intended as limiting. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the restrictions of the appended claims. 

1. An evaporator for a refrigeration system, comprising: a baffle plate extending over a portion of a tube bundle assembly, the baffle plate assisting in directing a fluid flow from a tube first portion to a tube second portion and preventing flow of liquid refrigerant from a suction nozzle.
 2. The evaporator of claim 1, the baffle plate defining in part a fluid passage extending from the tube first portion to the tube second portion.
 3. The evaporator of claim 1, the evaporator having a length dimension, the baffle plate extending a portion of the length dimension.
 4. The evaporator of claim 3, the baffle plate extending a portion of the length dimension equal to between a fourth and a third of the length dimension or between 2 feet to 4 feet.
 5. The evaporator of claim 1, a water pass vane defining a demarcation between the tube first portion and the tube second portion.
 6. The evaporator of claim 5, the water pass vane cooperating with baffle plate to in part define a fluid passage extending from the tube first portion to the tube second portion.
 7. The evaporator of claim 5, the water pass vane extending outward from a tube sheet a portion of a distance to a shell support plate.
 8. The evaporator of claim 7, a distal margin of the water pass vane being spaced apart from the shell support plate to in part define a fluid passage extending from the tube first portion to the tube second portion.
 9. The evaporator of claim 1, the baffle plate disposed overlying a top portion of the second tube portion.
 10. The evaporator of claim 1, the baffle plate having a proximal end sealingly coupled to a shell support plate and a distal end extending therefrom to overlie the tube bundle assembly.
 11. A method of forming an evaporator for a refrigeration system, comprising: extending a baffle plate over a portion of a tube bundle assembly and directing a fluid flow from a tube first portion to a tube second portion at least in part by means of the baffle plate.
 12. The method of claim 11, including defining in part a fluid passage extending from the tube first portion to the tube second portion by means of the baffle plate and water pass vane.
 13. The method of claim 11, the evaporator having a length dimension, including extending the baffle plate a portion of the length dimension.
 14. The method of claim 13, including extending the baffle plate a portion of the length dimension, the portion being equal to between a fourth and a third of the length dimension.
 15. The method of claim 11, including defining a demarcation between the tube first portion and the tube second portion by means of a water pass vane.
 16. The method of claim 15, including in part defining a fluid passage extending from the tube first portion to the tube second portion by means of the water pass vane cooperating with the baffle plate.
 17. The method of claim 15, including extending the water pass vane outward from a tube sheet a portion of a distance to a shell support plate.
 18. The method of claim 17, including spacing a distal margin of the water pass vane apart from the shell support plate and in part defining a fluid passage extending from the tube first portion to the tube second portion in the space defined between the water pass vane and the shell support plate.
 19. The method of claim 11, including disposing the baffle plate overlying a top portion of the second tube portion.
 20. The method of claim 11, sealingly coupling a baffle plate proximal end to a shell support plate and extending a baffle plate distal end therefrom to overlie the tube bundle assembly.
 21. The baffle plate can be installed at an angle so that the liquid refrigerant can flow back to the evaporator in case there is some liquid carried over the baffle plate. 